Tweak VideoListener doc

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=132433848

library/src/main/java/com/google/android/exoplayer2/SimpleExoPlayer.java

@@ -80,7 +80,7 @@ public final class SimpleExoPlayer implements ExoPlayer {
 
     /**
      * Called when a frame is rendered for the first time since setting the surface, and when a
-     * frame is rendered for the first time since video was enabled.
+     * frame is rendered for the first time since the renderer was reset.
      *
      * @param surface The {@link Surface} to which a first frame has been rendered.
      */